.tudou {
    /* box-sizing: border-box; */
    position: relative;
    width: 444px;
    height: 320px;
    background-color: pink;
    margin: 30px auto;
}

.tudou img {
    height: 100%;
    width: 100%;
}

.tudou::before {
    content: '';
    /* 隐藏遮罩层 */
    display: none;
    position: absolute;
    top: 0;
    left: 0;
    height: 100%;
    width: 100%;
    background: rgba(0, 0, 0, .4) url('/images/arr.png') no-repeat center;
}


/* 鼠标经过的时候显示真实的数据 */

.tudou:hover::before {
    display: block;
}